Gate-all-around integrated circuit structures fabricated using alternate etch selective material

ABSTRACT

Gate-all-around integrated circuit structures fabricated using alternate etch selective material, and the resulting structures, are described. For example, an integrated circuit structure includes a vertical arrangement of horizontal nanowires. A gate stack is over the vertical arrangement of horizontal nanowires. A pair of dielectric spacers is along sides of the gate stack and over the vertical arrangement of horizontal nanowires. A metal oxide material is between adjacent ones of the vertical arrangement of horizontal nanowires at a location between the pair of dielectric spacers and the sides of the gate stack.

TECHNICAL FIELD

Embodiments of the disclosure are in the field of integrated circuitstructures and processing and, in particular, gate-all-around integratedcircuit structures fabricated using alternate etch selective material,and the resulting structures.

BACKGROUND

For the past several decades, the scaling of features in integratedcircuits has been a driving force behind an ever-growing semiconductorindustry. Scaling to smaller and smaller features enables increaseddensities of functional units on the limited real estate ofsemiconductor chips. For example, shrinking transistor size allows forthe incorporation of an increased number of memory or logic devices on achip, lending to the fabrication of products with increased capacity.The drive for ever-more capacity, however, is not without issue. Thenecessity to optimize the performance of each device becomesincreasingly significant.

In the manufacture of integrated circuit devices, multi-gatetransistors, such as tri-gate transistors, have become more prevalent asdevice dimensions continue to scale down. In conventional processes,tri-gate transistors are generally fabricated on either bulk siliconsubstrates or silicon-on-insulator substrates. In some instances, bulksilicon substrates are preferred due to their lower cost and becausethey enable a less complicated tri-gate fabrication process. In anotheraspect, maintaining mobility improvement and short channel control asmicroelectronic device dimensions scale below the 10 nanometer (nm) nodeprovides a challenge in device fabrication. Nanowires used to fabricatedevices provide improved short channel control.

Scaling multi-gate and nanowire transistors has not been withoutconsequence, however. As the dimensions of these fundamental buildingblocks of microelectronic circuitry are reduced and as the sheer numberof fundamental building blocks fabricated in a given region isincreased, the constraints on the lithographic processes used to patternthese building blocks have become overwhelming. In particular, there maybe a trade-off between the smallest dimension of a feature patterned ina semiconductor stack (the critical dimension) and the spacing betweensuch features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1F illustrate cross-sectional views representing variousoperations in a method of fabricating a gate-all-around integratedcircuit structure using alternate etch selective material, in accordancewith an embodiment of the present disclosure.

FIG. 2 illustrates cross-sectional views, including exploded views,representing various operations in a method of fabricating agate-all-around integrated circuit structure using alternate etchselective material, in accordance with an embodiment of the presentdisclosure.

FIGS. 3A-3F illustrate cross-sectional views representing variousoperations in a method of fabricating a gate-all-around integratedcircuit structure, in accordance with an embodiment of the presentdisclosure.

FIGS. 4A-4J illustrates cross-sectional views of various operations in amethod of fabricating a gate-all-around integrated circuit structure, inaccordance with an embodiment of the present disclosure.

FIG. 5 illustrates a cross-sectional view of a non-planar integratedcircuit structure as taken along a gate line, in accordance with anembodiment of the present disclosure.

FIG. 6 illustrates cross-sectional views taken through nanowires andfins for a non-endcap architecture (left-hand side (a)) versus aself-aligned gate endcap (SAGE) architecture (right-hand side (b)), inaccordance with an embodiment of the present disclosure.

FIG. 7 illustrates cross-sectional views representing various operationsin a method of fabricating a self-aligned gate endcap (SAGE) structurewith gate-all-around devices, in accordance with an embodiment of thepresent disclosure.

FIG. 8A illustrates a three-dimensional cross-sectional view of ananowire-based integrated circuit structure, in accordance with anembodiment of the present disclosure.

FIG. 8B illustrates a cross-sectional source or drain view of thenanowire-based integrated circuit structure of FIG. 8A, as taken alongthe a-a′ axis, in accordance with an embodiment of the presentdisclosure.

FIG. 8C illustrates a cross-sectional channel view of the nanowire-basedintegrated circuit structure of FIG. 8A, as taken along the b-b′ axis,in accordance with an embodiment of the present disclosure.

FIG. 9 illustrates a computing device in accordance with oneimplementation of an embodiment of the disclosure.

FIG. 10 illustrates an interposer that includes one or more embodimentsof the disclosure.

DESCRIPTION OF THE EMBODIMENTS

Gate-all-around integrated circuit structures fabricated using alternateetch selective material, and the resulting structures, are described. Inthe following description, numerous specific details are set forth, suchas specific integration and material regimes, in order to provide athorough understanding of embodiments of the present disclosure. It willbe apparent to one skilled in the art that embodiments of the presentdisclosure may be practiced without these specific details. In otherinstances, well-known features, such as integrated circuit designlayouts, are not described in detail in order to not unnecessarilyobscure embodiments of the present disclosure. Furthermore, it is to beappreciated that the various embodiments shown in the Figures areillustrative representations and are not necessarily drawn to scale.

Certain terminology may also be used in the following description forthe purpose of reference only, and thus are not intended to be limiting.For example, terms such as “upper”, “lower”, “above”, and “below” referto directions in the drawings to which reference is made. Terms such as“front”, “back”, “rear”, and “side” describe the orientation and/orlocation of portions of the component within a consistent but arbitraryframe of reference which is made clear by reference to the text and theassociated drawings describing the component under discussion. Suchterminology may include the words specifically mentioned above,derivatives thereof, and words of similar import.

Embodiments described herein may be directed to front-end-of-line (FEOL)semiconductor processing and structures. FEOL is the first portion ofintegrated circuit (IC) fabrication where the individual devices (e.g.,transistors, capacitors, resistors, etc.) are patterned in thesemiconductor substrate or layer. FEOL generally covers everything up to(but not including) the deposition of metal interconnect layers.Following the last FEOL operation, the result is typically a wafer withisolated transistors (e.g., without any wires).

Embodiments described herein may be directed to back-end of line (BEOL)semiconductor processing and structures. BEOL is the second portion ofIC fabrication where the individual devices (e.g., transistors,capacitors, resistors, etc.) are interconnected with wiring on thewafer, e.g., the metallization layer or layers. BEOL includes contacts,insulating layers (dielectrics), metal levels, and bonding sites forchip-to-package connections. In the BEOL part of the fabrication stagecontacts (pads), interconnect wires, vias and dielectric structures areformed. For modern IC processes, more than 10 metal layers may be addedin the BEOL.

Embodiments described below may be applicable to FEOL processing andstructures, BEOL processing and structures, or both FEOL and BEOLprocessing and structures. In particular, although an exemplaryprocessing scheme may be illustrated using a FEOL processing scenario,such approaches may also be applicable to BEOL processing. Likewise,although an exemplary processing scheme may be illustrated using a BEOLprocessing scenario, such approaches may also be applicable to FEOLprocessing.

One or more embodiments described herein are directed to silicon/etchselective material (Si/ESM) nanowire/nanoribbon (NW/NR) fabrication toachieve precise dimple etch for gate spacer integration.

To provide context, in nanowire (NW) and nanoribbon (NR) transistorarchitectures, the precise control of a dimple etch as well as NW/NRrelease etch are of profound importance. A shift in etch properties canpotentially impact NW/NR channel thickness, channel to gate (CTG)leakage/shorting and overlap capacitance owing to precise spacerthickness control. This can be realized only with high etch selectivitybetween Si and SiGe which is a huge challenge owing to similar materialproperties and the presence of various other materials in adjacentareas. Embodiments described herein include a process flow that canenable higher etch selectivity as well as etch control, e.g., byreplacing a SiGe sacrificial material with a replacement selectivematerial up front in the process flow.

Previous approaches used in a process flow have utilized etchselectivity between Si and SiGe materials. However, the inter-diffusionbetween Si and SiGe materials can render such a selective etch as lessselective resulting in thinner than planned NWs/NRs because Si and SiGetend to intermix. In accordance with one or more embodiments of thepresent disclosure, approaches are described for addressing the etchselectivity issue between SiGe and Si channel materials. An exemplaryintegration scheme involves replacing a SiGe material with and alternateetch selective material (ESM) post fin (NW/NR) patterning. By addingclamping pillars for mechanical stability to the structure, the SiGe canbe selectively etched away first. The material for the clamping pillarcan be chosen based on the etch chemistry with highest Si to SiGeselectivity. Once the SiGe material is etched away, the empty spaces canbe filled with an alternate material of choice with high dimple etchselectivity to the rest of the materials exposed.

Advantages of implementing embodiments described herein can include thereplacement of a SiGe interlayer with an ESM early in the process flow(post Fin patterning) to readily access the SiGe material from thelateral direction. With the pillars sufficiently separated, thevariation of etch rate depending on the fin pitch will be less critical.Further, there will be few exposed materials during the etch, such asonly Si/SiGe NW/NR imposing less restrictions on selective etch of SiGematerial. In an embodiment, the presence of the ESM will be detectablefrom the remaining ESM at the corners of a gate spacer and channel. Theminute amounts of ESM, such as a metal oxide, e.g., TiOx, TaOx, AlOx(owing to their etch selectivity towards SiOx, SiN, Si), can be tracedusing analytical techniques like EDX maps of TEM, SIMS and Atom ProbeTomography.

As an exemplary processing scheme, FIGS. 1A-1F illustratecross-sectional views representing various operations in a method offabricating a gate-all-around integrated circuit structure usingalternate etch selective material, in accordance with an embodiment ofthe present disclosure. For each FIGS. 1A, 1B, 1C, 1D, 1E and 1F, across-sectional view of a pillar cut (top), a cross-sectional view of afin cut under the pillar (middle), and a cross-sectional view of a fincut between pillars (bottom) is shown.

Referring to FIG. 1A, a plurality of alternating active layers 106 andfirst sacrificial layers 104 are formed above a substrate 102, such as abulk silicon substrate. In an embodiment, the active layers includesilicon, and the first sacrificial layers include silicon germanium. Theplurality of alternating active layers 106 and first sacrificial layers104 is patterned to form one or more fins, such as fins 108 and 110.

Referring to FIG. 1B, one or more sacrificial clamping pillars 112 areformed over the one or more fins, such as fins 108 and 110.

Referring to FIG. 1C, the first sacrificial layers 104 are removed fromthe one or more fins, such as fins 108 and 110, to form one or morecorresponding fins having first sacrificial layers 104 removedtherefrom, such as fins 114 and 116.

Referring to FIG. 1D, a second sacrificial material 118 is formed overthe structure of FIG. 1C, including in locations previously occupied bythe first sacrificial layers 104. One or more corresponding fins havingsecond sacrificial material 118 therein are thus formed, such as fins120 and 122.

Referring to FIG. 1E, the second sacrificial material 118 is patternedto leave second sacrificial layers 124 in place of the first sacrificiallayers 104 in corresponding one or more fins, such as fins 126 and 128.In an embodiment, the second sacrificial layers 124 include a metaloxide selected from the group consisting of titanium oxide (TiOx),tantalum oxide (TaOx) and aluminum oxide (AlOx). In one embodiment, amixture or combination of such species can be used, such as TiAlOx.

Referring to FIG. 1F, the one or more sacrificial clamping pillars 112are removed. The structure of FIG. 1F may then be used in agate-all-around fabrication process, examples of which are describedbelow.

As another exemplary processing scheme, FIG. 2 illustratescross-sectional views, including exploded views, representing variousoperations in a method of fabricating a gate-all-around integratedcircuit structure using alternate etch selective material, in accordancewith an embodiment of the present disclosure.

Referring to part (a) of FIG. 2, sacrificial clamping structures 204/206are shown over a plurality of alternating active layers 106 and secondsacrificial layers 124 above a substrate 102, such as described above.The clamping structures 204/206 can include a dummy gate structure 204and thick dummy spacers 206. In the particular embodiment shown, aprotective cap 202 is included on the plurality of alternating activelayers 106 and second sacrificial layers 124.

Referring to part (b) of FIG. 2, fins 208 are patterned into theplurality of alternating active layers 106 and second sacrificial layers124 using the sacrificial clamping structures 204/206 as a mask. Thepatterning forms patterned active layers 106′, patterned secondsacrificial layers 124′, and patterned protective cap 202′.

Referring to part (c) of FIG. 2, the patterned second sacrificial layers124′ are recessed relative to the patterned active layers 106′ to formfins 208′ having recessed patterned second sacrificial layers 124″. Withrespect to region 210 highlighted in part (c) of FIG. 2, there is highetch selectivity between the patterned active layers 106′ and the etchselective material (ESM) of the patterned second sacrificial layers124′. The result is relatively lower nanowire/nanoribbon loss, and aprecise dimple shape, as seen in the exploded portion (I) of part (c) ofFIG. 2.

Referring to part (d) of FIG. 2, the thick dummy spacers 206 are removedand replaced with sidewalls spacers 236 and corresponding internalspacers 212. The patterned active layers 106′ are then patterned asecond time to form fins 208″ having twice patterned active layers 106″using the dummy gate structure 204/sidewall spacers 236/212 as a mask.The internal spacers 212 are formed conformal with the precise dimpleshape of recessed patterned second sacrificial layers 124″, as seen inthe exploded portion (II) of part (d) of FIG. 2.

Referring to part (e) of FIG. 2, an interlayer dielectric material 214is formed over the structure of part (d), and the dummy gate structures204 are removed. In one such embodiment, as is depicted, epitaxialsource or drain regions 218 are formed on the structure of part (d)prior to forming interlayer dielectric material 214. The recessedpatterned second sacrificial layers 124″ are removed in locations of theremoved dummy gate structures 204 to release nanowire portions of thetwice patterned active layers 106″. As seen in the exploded portions(III) and (IV) of part (e) of FIG. 2, the removal of the recessedpatterned second sacrificial layers 124″ in locations of the removeddummy gate structures 204 can leave residual metal oxide material 124′in the resulting structure. Although not depicted, a permanent gatestructure can then formed over the nanowire portions of the twicepatterned active layers 106″ between the sidewall spacers 236/212.

With reference again to part (e) of FIG. 2 and associated concepts, inaccordance with an embodiment, of the present disclosure, an integratedcircuit structure includes a vertical arrangement of horizontalnanowires 106″. A gate stack (not depicted, but would be in location216) is over the vertical arrangement of horizontal nanowires 106″. Apair of dielectric spacers 236/212 is along sides of the gate stack andover the vertical arrangement of horizontal nanowires 106″. A metaloxide material 124′ is between adjacent ones of the vertical arrangementof horizontal nanowires 106″ at a location between the pair ofdielectric spacers 236/212 and the sides of the gate stack.

In an embodiment, the metal oxide material 124′″ is a metal oxideselected from the group consisting of titanium oxide (TiOx), tantalumoxide (TaOx) and aluminum oxide (AlOx). In an embodiment, the pair ofdielectric spacers 236/212 includes a dielectric material selected fromthe group consisting of silicon nitride, silicon oxynitride, siliconoxide, and carbon-doped silicon nitride.

In an embodiment, the gate stack includes a high-k gate dielectric layerand a metal gate electrode. In one such embodiment, the high-k gatedielectric layer includes a metal oxide gate dielectric materialdifferent than the metal oxide material.

In an embodiment, the integrated circuit structure further includes apair of epitaxial source or drain structures 218 at first and secondends of the vertical arrangement of horizontal nanowires 106″. In onesuch embodiment, the pair of epitaxial source or drain structures 218 isa pair of discrete epitaxial source or drain structures, as is depicted,and examples of which are described in greater detail below. In anothersuch embodiment, the pair of epitaxial source or drain structures 218 isa pair of non-discrete epitaxial source or drain structures, examples ofwhich are described in greater detail below.

In an embodiment, the vertical arrangement of horizontal nanowires 106″is over a subfin (e.g., where 208 is an upper portion of a finprotruding from an underlying substrate, and the fin further includes asubfin portion). In one such embodiment, the metal oxide material 124′″is further between the subfin and a bottommost nanowire of the verticalarrangement of horizontal nanowires 106″ at a location between the pairof dielectric spacers 236/212 and the sides of the gate stack.

In an embodiment, the subfin includes a portion of a bulk siliconsubstrate. In an embodiment, the nanowires 106″ of the verticalarrangement of horizontal nanowires include silicon.

It is to be appreciated, in a particular embodiment, channel layers maybe silicon, and intervening layers may be silicon germanium. As usedthroughout, a silicon layer may be used to describe a silicon materialcomposed of a very substantial amount of, if not all, silicon. However,it is to be appreciated that, practically, 100% pure Si may be difficultto form and, hence, could include a tiny percentage of carbon, germaniumor tin. Such impurities may be included as an unavoidable impurity orcomponent during deposition of Si or may “contaminate” the Si upondiffusion during post deposition processing. As such, embodimentsdescribed herein directed to a silicon layer may include a silicon layerthat contains a relatively small amount, e.g., “impurity” level, non-Siatoms or species, such as Ge, C or Sn. It is to be appreciated that asilicon layer as described herein may be undoped or may be doped withdopant atoms such as boron, phosphorous or arsenic.

As used throughout, a silicon germanium layer may be used to describe asilicon germanium material composed of substantial portions of bothsilicon and germanium, such as at least 5% of both. In some embodiments,the amount of germanium is greater than the amount of silicon. Inparticular embodiments, a silicon germanium layer includes approximately60% germanium and approximately 40% silicon (Si₄₀Ge₆₀). In otherembodiments, the amount of silicon is greater than the amount ofgermanium. In particular embodiments, a silicon germanium layer includesapproximately 30% germanium and approximately 70% silicon (Si₇₀Ge₃₀). Itis to be appreciated that, practically, 100% pure silicon germanium(referred to generally as SiGe) may be difficult to form and, hence,could include a tiny percentage of carbon or tin. Such impurities may beincluded as an unavoidable impurity or component during deposition ofSiGe or may “contaminate” the SiGe upon diffusion during post depositionprocessing. As such, embodiments described herein directed to a silicongermanium layer may include a silicon germanium layer that contains arelatively small amount, e.g., “impurity” level, non-Ge and non-Si atomsor species, such as carbon or tin. It is to be appreciated that asilicon germanium layer as described herein may be undoped or may bedoped with dopant atoms such as boron, phosphorous or arsenic.

Described below are various processing schemes and devices that mayinvolve a gate-all-around integrated circuit structure fabricated usingalternate etch selective material. It is to be appreciated that theexemplary embodiments need not necessarily require all featuresdescribed, or may include more features than are described.

As an exemplary process flow for fabricating a gate-all-around device ofa gate-all-around integrated circuit structure having a device withchannel-to-substrate electrical contact, FIGS. 3A-3F illustratecross-sectional views representing various operations in a method offabricating a gate-all-around integrated circuit structure, inaccordance with an embodiment of the present disclosure.

Referring to FIG. 3A, a starting structure may include a defectmodification layer 304 formed on a substrate 302. In one embodiment,during processing, a silicon (Si) substrate 302 is first modified toallow subsequent buffer layers to easily relax, as well as to trapdefects that otherwise promote relaxation below what will become thechannel material. In one embodiment, the defect modification layer 304is a layer including ion implant damage or is a defect-rich Si growthlayer, or a combination thereof. In another embodiment, the layer 304 isa defect-rich SiGe layer.

Referring to FIG. 3B, a relaxed buffer layer 306 is grown on the defectmodification layer 304. In an embodiment, the relaxed buffer layer 306is a relaxed Si₇₀Ge₃₀ layer.

Referring to FIG. 3C, a sacrificial layer 308 is grown on the relaxedbuffer layer 306. In an embodiment, the sacrificial layer 308 is aSi₇₀Ge₃₀ layer. In one embodiment, the sacrificial layer 308 has acomposition the same as or substantially the same as the relaxed bufferlayer 306. In a particular embodiment, the sacrificial layer 308 is aSi₇₀Ge₃₀ layer and the relaxed buffer layer 306 is a relaxed Si₇₀Ge₃₀layer. In one embodiment, the sacrificial layer 308 is formed bycontinuing growth relaxed buffer layer 306 in a same deposition process,and the sacrificial layer 308 and growth relaxed buffer layer 306 mayappear as a unified layer. In another embodiment, the sacrificial layer308 has a composition different from the relaxed buffer layer 306.

Alternating channel layers 310 and intervening sacrificial layers 312are formed on the sacrificial layer 308. In an embodiment, the channellayers 310 are Si₄₀Ge₆₀ channel layers. In an embodiment, theintervening sacrificial layers 312 are intervening Si₇₀Ge₃₀ layer.

Referring to FIG. 3D, the stack of materials of FIG. 3D have a patternedmask 314/316 formed thereon, which may include a hardmask portion 316and an etch stop portion 314. The patterned mask 314/316 is used to etcha plurality of fins in the stack of materials of FIG. 3D. In anembodiment, the etching is deeper than the defect modification layer304. In one such embodiment, each fin includes a patterned substrateportion 322, a defect modification layer 324, a buffer layer 326, asacrificial layer 328, channel layers 330, and intervening sacrificiallayers 332.

In accordance with an embodiment of the present disclosure, between theoperations of FIGS. 3D and 3E, intervening sacrificial layers 332 and,possibly, the sacrificial layer 328 are replaced with second sacrificiallayers, such as described in association with FIGS. 1A-1F and FIG. 2. Inan embodiment, the second sacrificial layers include a metal oxideselected from the group consisting of titanium oxide (TiOx), tantalumoxide (TaOx) and aluminum oxide (AlOx). In one embodiment, a mixture orcombination of such species can be used, such as TiAlOx.

Referring to FIG. 3E, isolation structures 334, such as shallow trenchisolation structures, are formed between fins. Dummy gate structures arethen formed over the fins and over the isolation structures 334. Each ofthe dummy gate structures includes a dummy gate electrode 346, ahardmask 348, sidewall spacers 350, and a dielectric helmet 352. A dummygate dielectric may also be included beneath the dummy gate electrode346, as is depicted. In one embodiment, the dummy gate dielectric is aremnant of the mask layer 314.

Referring again to FIG. 3E, the dummy gate structures are used as a maskto etch trenches into exposed portions of the fins, e.g., into sourceand drain regions of the fins. The etching removes portions of channellayers 330 to form channel layers 340, and removes portions of theintervening sacrificial layers 332 to form intervening sacrificiallayers 342. In one embodiment, the etching extends at least partiallyinto sacrificial layer 328 to form recessed sacrificial layer 338.

Referring again to FIG. 3E, epitaxial source or drain structures 344 arethen grown in the trenches. In an embodiment, the epitaxial source ordrain structures provide strain for the channel layers 340.

Referring to FIG. 3F, following source/drain deposition, the dummy gateelectrode 346 and the sacrificial layers 342 are removed and replacedwith a permanent gate electrode 370 and gate dielectric stack 372. Inone embodiment, the gate electrode 370 is a metal gate electrode, andthe gate dielectric 372 is a high-k gate dielectric. In an embodiment, aportion of the recessed sacrificial layer 338 is further recessed in thegate channel region to form a gate electrode 370 in a further recessedsacrificial layer 358, where the gate electrode 370 is deeper than theepitaxial source or drain structures 344, as is depicted. In anembodiment, portions 362 of the sacrificial layers 342 are retained oneither side of the gate electrode 370, as is also depicted. In anembodiment, a contact barrier layer 374 and conductive fill 376 areformed over the epitaxial source or drain structures 344. It is to beappreciated that the structure of FIG. 3F may be further planarized inorder to confine the permanent gate material 370 to the gate locations.

Accordingly, nanowire release processing may be performed through areplacement gate trench. Additional examples of such release processesare described below. Additionally, in yet another aspect, backend (BE)interconnect scaling can result in lower performance and highermanufacturing cost due to patterning complexity. Embodiments describedherein may be implemented to enable front-side and back-sideinterconnect integration for nanowire transistors. Embodiments describedherein may provide an approach to achieve a relatively widerinterconnect pitch. The result may be improved product performance andlower patterning costs. Embodiments may be implemented to enable robustfunctionality of scaled nanowire or nanoribbon transistors with lowpower and high performance.

One or more embodiments described herein are directed dual epitaxial(EPI) connections for nanowire or nanoribbon transistors using partialsource or drain (SD) and asymmetric trench contact (TCN) depth. In anembodiment, an integrated circuit structure is fabricated by formingsource-drain openings of nanowire/nanoribbon transistors which arepartially filled with SD epitaxy. A remainder of the opening is filledwith a conductive material. Deep trench formation on one of the sourceor drain side enables direct contact to a back-side interconnect level.

As an exemplary process flow for fabricating a gate-all-around device ofa gate-all-around integrated circuit structure having a device withchannel-to-substrate electrical contact, FIGS. 4A-4J illustratescross-sectional views of various operations in a method of fabricating agate-all-around integrated circuit structure, in accordance with anembodiment of the present disclosure.

Referring to FIG. 4A, a method of fabricating an integrated circuitstructure includes forming a starting stack which includes alternatingsacrificial layers 404 and nanowires 406 above a fin 402, such as asilicon fin. The nanowires 406 may be referred to as a verticalarrangement of nanowires. A protective cap 408 may be formed above thealternating sacrificial layers 404 and nanowires 406, as is depicted. Arelaxed buffer layer 452 and a defect modification layer 450 may beformed beneath the alternating sacrificial layers 404 and nanowires 406,as is also depicted.

In accordance with an embodiment of the present disclosure, between theoperations of FIGS. 4A and 4B, sacrificial layers 404 are replaced withsecond sacrificial layers, such as described in association with FIGS.1A-1F and FIG. 2. In an embodiment, the second sacrificial layersinclude a metal oxide selected from the group consisting of titaniumoxide (TiOx), tantalum oxide (TaOx) and aluminum oxide (AlOx). In oneembodiment, a mixture or combination of such species can be used, suchas TiAlOx.

Referring to FIG. 4B, a gate stack 410 is formed over the verticalarrangement of horizontal nanowires 406. Portions of the verticalarrangement of horizontal nanowires 406 are then released by removingportions of the sacrificial layers 404 to provide recessed sacrificiallayers 404′ and cavities 412, as is depicted in FIG. 4C.

It is to be appreciated that the structure of FIG. 4C may be fabricatedto completion without first performing the deep etch and asymmetriccontact processing described below. In either case (e.g., with orwithout asymmetric contact processing), in an embodiment, a fabricationprocess involves use of a process scheme that provides a gate-all-aroundintegrated circuit structure having epitaxial nubs, which may bevertically discrete source or drain structures.

Referring to FIG. 4D, upper gate spacers 414 are formed at sidewalls ofthe gate structure 410. Cavity spacers 416 are formed in the cavities412 beneath the upper gate spacers 414. A deep trench contact etch isthen optionally performed to form trenches 418 and to form recessednanowires 406′. A patterned relaxed buffer layer 452′ and a patterneddefect modification layer 450′ may also be present, as is depicted. Asacrificial material 420 is then formed in the trenches 418, as isdepicted in FIG. 4E. In other process schemes, an isolated trench bottomor silicon trench bottom may be used.

Referring to FIG. 4F, a first epitaxial source or drain structure (e.g.,left-hand features 422) is formed at a first end of the verticalarrangement of horizontal nanowires 406′. A second epitaxial source ordrain structure (e.g., right-hand features 422) is formed at a secondend of the vertical arrangement of horizontal nanowires 406′. In anembodiment, as depicted, the epitaxial source or drain structures 422are vertically discrete source or drain structures and may be referredto as epitaxial nubs.

An inter-layer dielectric (ILD) material 424 is then formed at the sidesof the gate electrode 410 and adjacent the source or drain structures422, as is depicted in FIG. 4G. Referring to FIG. 4H, a replacement gateprocess is used to form a permanent gate dielectric 428 and a permanentgate electrode 426. The ILD material 424 is then removed, as is depictedin FIG. 4I. The sacrificial material 420 is then removed from one of thesource drain locations (e.g., right-hand side) to form trench 432, butis not removed from the other of the source drain locations to formtrench 430.

Referring to FIG. 4J, a first conductive contact structure 434 is formedcoupled to the first epitaxial source or drain structure (e.g.,left-hand features 422). A second conductive contact structure 436 isformed coupled to the second epitaxial source or drain structure (e.g.,right-hand features 422). The second conductive contact structure 436 isformed deeper along the fin 402 than the first conductive contactstructure 434. In an embodiment, although not depicted in FIG. 4J, themethod further includes forming an exposed surface of the secondconductive contact structure 436 at a bottom of the fin 402. Conductivecontacts may include a contact resistance reducing layer and a primarycontact electrode layer, where examples can include Ti, Ni, Co (for theformer and W, Ru, Co for the latter.)

In an embodiment, the second conductive contact structure 436 is deeperalong the fin 402 than the first conductive contact structure 434, as isdepicted. In one such embodiment, the first conductive contact structure434 is not along the fin 402, as is depicted. In another suchembodiment, not depicted, the first conductive contact structure 434 ispartially along the fin 402.

In an embodiment, the second conductive contact structure 436 is alongan entirety of the fin 402. In an embodiment, although not depicted, inthe case that the bottom of the fin 402 is exposed by a back-sidesubstrate removal process, the second conductive contact structure 436has an exposed surface at a bottom of the fin 402.

In another aspect, in order to enable access to both conductive contactstructures of a pair of asymmetric source and drain contact structures,integrated circuit structures described herein may be fabricated using aback-side reveal of front-side structures fabrication approach. In someexemplary embodiments, reveal of the back-side of a transistor or otherdevice structure entails wafer-level back-side processing. In contrastto a conventional TSV-type technology, a reveal of the back-side of atransistor as described herein may be performed at the density of thedevice cells, and even within sub-regions of a device. Furthermore, sucha reveal of the back-side of a transistor may be performed to removesubstantially all of a donor substrate upon which a device layer wasdisposed during front-side device processing. As such, a microns-deepTSV becomes unnecessary with the thickness of semiconductor in thedevice cells following a reveal of the back-side of a transistorpotentially being only tens or hundreds of nanometers.

Reveal techniques described herein may enable a paradigm shift from“bottom-up” device fabrication to “center-out” fabrication, where the“center” is any layer that is employed in front-side fabrication,revealed from the back-side, and again employed in back-sidefabrication. Processing of both a front-side and revealed back-side of adevice structure may address many of the challenges associated withfabricating 3D ICs when primarily relying on front-side processing.

A reveal of the back-side of a transistor approach may be employed forexample to remove at least a portion of a carrier layer and interveninglayer of a donor-host substrate assembly. The process flow begins withan input of a donor-host substrate assembly. A thickness of a carrierlayer in the donor-host substrate is polished (e.g., CMP) and/or etchedwith a wet or dry (e.g., plasma) etch process. Any grind, polish, and/orwet/dry etch process known to be suitable for the composition of thecarrier layer may be employed. For example, where the carrier layer is agroup IV semiconductor (e.g., silicon) a CMP slurry known to be suitablefor thinning the semiconductor may be employed. Likewise, any wetetchant or plasma etch process known to be suitable for thinning thegroup IV semiconductor may also be employed.

In some embodiments, the above is preceded by cleaving the carrier layeralong a fracture plane substantially parallel to the intervening layer.The cleaving or fracture process may be utilized to remove a substantialportion of the carrier layer as a bulk mass, reducing the polish or etchtime needed to remove the carrier layer. For example, where a carrierlayer is 400-900 μm in thickness, 100-700 μm may be cleaved off bypracticing any blanket implant known to promote a wafer-level fracture.In some exemplary embodiments, a light element (e.g., H, He, or Li) isimplanted to a uniform target depth within the carrier layer where thefracture plane is desired. Following such a cleaving process, thethickness of the carrier layer remaining in the donor-host substrateassembly may then be polished or etched to complete removal.Alternatively, where the carrier layer is not fractured, the grind,polish and/or etch operation may be employed to remove a greaterthickness of the carrier layer.

Next, exposure of an intervening layer is detected. Detection is used toidentify a point when the back-side surface of the donor substrate hasadvanced to nearly the device layer. Any endpoint detection techniqueknown to be suitable for detecting a transition between the materialsemployed for the carrier layer and the intervening layer may bepracticed. In some embodiments, one or more endpoint criteria are basedon detecting a change in optical absorbance or emission of the back-sidesurface of the donor substrate during the polishing or etchingperformed. In some other embodiments, the endpoint criteria areassociated with a change in optical absorbance or emission of byproductsduring the polishing or etching of the donor substrate back-sidesurface. For example, absorbance or emission wavelengths associated withthe carrier layer etch byproducts may change as a function of thedifferent compositions of the carrier layer and intervening layer. Inother embodiments, the endpoint criteria are associated with a change inmass of species in byproducts of polishing or etching the back-sidesurface of the donor substrate. For example, the byproducts ofprocessing may be sampled through a quadrupole mass analyzer and achange in the species mass may be correlated to the differentcompositions of the carrier layer and intervening layer. In anotherexemplary embodiment, the endpoint criteria is associated with a changein friction between a back-side surface of the donor substrate and apolishing surface in contact with the back-side surface of the donorsubstrate.

Detection of the intervening layer may be enhanced where the removalprocess is selective to the carrier layer relative to the interveninglayer as non-uniformity in the carrier removal process may be mitigatedby an etch rate delta between the carrier layer and intervening layer.Detection may even be skipped if the grind, polish and/or etch operationremoves the intervening layer at a rate sufficiently below the rate atwhich the carrier layer is removed. If an endpoint criteria is notemployed, a grind, polish and/or etch operation of a predetermined fixedduration may stop on the intervening layer material if the thickness ofthe intervening layer is sufficient for the selectivity of the etch. Insome examples, the carrier etch rate: intervening layer etch rate is3:1-10:1, or more.

Upon exposing the intervening layer, at least a portion of theintervening layer may be removed. For example, one or more componentlayers of the intervening layer may be removed. A thickness of theintervening layer may be removed uniformly by a polish, for example.Alternatively, a thickness of the intervening layer may be removed witha masked or blanket etch process. The process may employ the same polishor etch process as that employed to thin the carrier, or may be adistinct process with distinct process parameters. For example, wherethe intervening layer provides an etch stop for the carrier removalprocess, the latter operation may employ a different polish or etchprocess that favors removal of the intervening layer over removal of thedevice layer. Where less than a few hundred nanometers of interveninglayer thickness is to be removed, the removal process may be relativelyslow, optimized for across-wafer uniformity, and more preciselycontrolled than that employed for removal of the carrier layer. A CMPprocess employed may, for example employ a slurry that offers very highselectively (e.g., 100:1-300:1, or more) between semiconductor (e.g.,silicon) and dielectric material (e.g., SiO) surrounding the devicelayer and embedded within the intervening layer, for example, aselectrical isolation between adjacent device regions.

For embodiments where the device layer is revealed through completeremoval of the intervening layer, back-side processing may commence onan exposed back-side of the device layer or specific device regionsthere in. In some embodiments, the back-side device layer processingincludes a further polish or wet/dry etch through a thickness of thedevice layer disposed between the intervening layer and a device regionpreviously fabricated in the device layer, such as a source or drainregion.

In some embodiments where the carrier layer, intervening layer, ordevice layer back-side is recessed with a wet and/or plasma etch, suchan etch may be a patterned etch or a materially selective etch thatimparts significant non-planarity or topography into the device layerback-side surface. As described further below, the patterning may bewithin a device cell (i.e., “intra-cell” patterning) or may be acrossdevice cells (i.e., “inter-cell” patterning). In some patterned etchembodiments, at least a partial thickness of the intervening layer isemployed as a hard mask for back-side device layer patterning. Hence, amasked etch process may preface a correspondingly masked device layeretch.

The above described processing scheme may result in a donor-hostsubstrate assembly that includes IC devices that have a back-side of anintervening layer, a back-side of the device layer, and/or back-side ofone or more semiconductor regions within the device layer, and/orfront-side metallization revealed. Additional back-side processing ofany of these revealed regions may then be performed during downstreamprocessing.

It is to be appreciated that the structures resulting from the aboveexemplary processing schemes may be used in a same or similar form forsubsequent processing operations to complete device fabrication, such asPMOS and/or NMOS device fabrication. As an example of a completeddevice, FIG. 5 illustrate a cross-sectional view of a non-planarintegrated circuit structure as taken along a gate line, in accordancewith an embodiment of the present disclosure.

Referring to FIG. 5, a semiconductor structure or device 500 includes anon-planar active region (e.g., a fin structure including protruding finportion 504 and sub-fin region 505) within a trench isolation region506. In an embodiment, instead of a solid fin, the non-planar activeregion is separated into nanowires (such as nanowires 504A and 504B)above sub-fin region 505, as is represented by the dashed lines. Ineither case, for ease of description for non-planar integrated circuitstructure 500, a non-planar active region 504 is referenced below as aprotruding fin portion. In an embodiment, the sub-fin region 505 alsoincludes a relaxed buffer layer 592 and a defect modification layer 590,as is depicted.

A gate line 508 is disposed over the protruding portions 504 of thenon-planar active region (including, if applicable, surroundingnanowires 504A and 504B), as well as over a portion of the trenchisolation region 506. As shown, gate line 508 includes a gate electrode550 and a gate dielectric layer 552. In one embodiment, gate line 508may also include a dielectric cap layer 554. A gate contact 514, andoverlying gate contact via 516 are also seen from this perspective,along with an overlying metal interconnect 560, all of which aredisposed in inter-layer dielectric stacks or layers 570. Also seen fromthe perspective of FIG. 5, the gate contact 514 is, in one embodiment,disposed over trench isolation region 506, but not over the non-planaractive regions. In another embodiment, the gate contact 514 is over thenon-planar active regions.

In an embodiment, the semiconductor structure or device 500 is anon-planar device such as, but not limited to, a fin-FET device, atri-gate device, a nanoribbon device, or a nanowire device. In such anembodiment, a corresponding semiconducting channel region is composed ofor is formed in a three-dimensional body. In one such embodiment, thegate electrode stacks of gate lines 508 surround at least a top surfaceand a pair of sidewalls of the three-dimensional body.

As is also depicted in FIG. 5, in an embodiment, an interface 580 existsbetween a protruding fin portion 504 and sub-fin region 505. Theinterface 580 can be a transition region between a doped sub-fin region505 and a lightly or undoped upper fin portion 504. In one suchembodiment, each fin is approximately 10 nanometers wide or less, andsub-fin dopants are optionally supplied from an adjacent solid statedoping layer at the sub-fin location. In a particular such embodiment,each fin is less than 10 nanometers wide.

Although not depicted in FIG. 5, it is to be appreciated that source ordrain regions of or adjacent to the protruding fin portions 504 are oneither side of the gate line 508, i.e., into and out of the page. In oneembodiment, the material of the protruding fin portions 504 in thesource or drain locations is removed and replaced with anothersemiconductor material, e.g., by epitaxial deposition to form epitaxialsource or drain structures. The source or drain regions may extend belowthe height of dielectric layer of trench isolation region 506, i.e.,into the sub-fin region 505. In accordance with an embodiment of thepresent disclosure, the more heavily doped sub-fin regions, i.e., thedoped portions of the fins below interface 580, inhibits source to drainleakage through this portion of the bulk semiconductor fins. In anembodiment, the source and drain regions have associated asymmetricsource and drain contact structures, as described above in associationwith FIG. 4J.

With reference again to FIG. 5, in an embodiment, fins 504/505 (and,possibly nanowires 504A and 504B) are composed of a crystalline silicongermanium layer which may be doped with a charge carrier, such as butnot limited to phosphorus, arsenic, boron, gallium or a combinationthereof.

In an embodiment, trench isolation region 506, and trench isolationregions (trench isolations structures or trench isolation layers)described throughout, may be composed of a material suitable toultimately electrically isolate, or contribute to the isolation of,portions of a permanent gate structure from an underlying bulk substrateor isolate active regions formed within an underlying bulk substrate,such as isolating fin active regions. For example, in one embodiment,trench isolation region 506 is composed of a dielectric material suchas, but not limited to, silicon dioxide, silicon oxy-nitride, siliconnitride, or carbon-doped silicon nitride.

Gate line 508 may be composed of a gate electrode stack which includes agate dielectric layer 552 and a gate electrode layer 550. In anembodiment, the gate electrode of the gate electrode stack is composedof a metal gate and the gate dielectric layer 552 is composed of ahigh-k material. For example, in one embodiment, the gate dielectriclayer 552 is composed of a material such as, but not limited to, hafniumoxide, hafnium oxy-nitride, hafnium silicate, lanthanum oxide, zirconiumoxide, zirconium silicate, tantalum oxide, barium strontium titanate,barium titanate, strontium titanate, yttrium oxide, aluminum oxide, leadscandium tantalum oxide, lead zinc niobate, or a combination thereof.Furthermore, a portion of gate dielectric layer 552 may include a layerof native oxide formed from the top few layers of the substrate fin 504.In an embodiment, the gate dielectric layer 552 is composed of a tophigh-k portion and a lower portion composed of an oxide of asemiconductor material. In one embodiment, the gate dielectric layer 552is composed of a top portion of hafnium oxide and a bottom portion ofsilicon dioxide or silicon oxy-nitride. In some implementations, aportion of the gate dielectric is a “U”-shaped structure that includes abottom portion substantially parallel to the surface of the substrateand two sidewall portions that are substantially perpendicular to thetop surface of the substrate.

In one embodiment, the gate electrode layer 550 is composed of a metallayer such as, but not limited to, metal nitrides, metal carbides, metalsilicides, metal aluminides, hafnium, zirconium, titanium, tantalum,aluminum, ruthenium, palladium, platinum, cobalt, nickel or conductivemetal oxides. In a specific embodiment, the gate electrode layer 550 iscomposed of a non-workfunction-setting fill material formed above ametal workfunction-setting layer. The gate electrode layer 550 mayconsist of a P-type workfunction metal or an N-type workfunction metal,depending on whether the transistor is to be a PMOS or an NMOStransistor. In some implementations, the gate electrode layer 550 mayconsist of a stack of two or more metal layers, where one or more metallayers are workfunction metal layers and at least one metal layer is aconductive fill layer. For a PMOS transistor, metals that may be usedfor the gate electrode include, but are not limited to, ruthenium,palladium, platinum, cobalt, nickel, and conductive metal oxides, e.g.,ruthenium oxide. A P-type metal layer will enable the formation of aPMOS gate electrode with a workfunction that is between about 4.9 eV andabout 5.2 eV. For an NMOS transistor, metals that may be used for thegate electrode include, but are not limited to, hafnium, zirconium,titanium, tantalum, aluminum, alloys of these metals, and carbides ofthese metals such as hafnium carbide, zirconium carbide, titaniumcarbide, tantalum carbide, and aluminum carbide. An N-type metal layerwill enable the formation of an NMOS gate electrode with a workfunctionthat is between about 3.9 eV and about 4.2 eV. In some implementations,the gate electrode layer 550 may consist of a “U”-shaped structure thatincludes a bottom portion substantially parallel to the surface of thesubstrate and two sidewall portions that are substantially perpendicularto the top surface of the substrate. In another implementation, at leastone of the metal layers that form the gate electrode layer 550 maysimply be a planar layer that is substantially parallel to the topsurface of the substrate and does not include sidewall portionssubstantially perpendicular to the top surface of the substrate. Infurther implementations of the disclosure, the gate electrode layer 550may consist of a combination of U-shaped structures and planar,non-U-shaped structures. For example, the gate electrode layer 550 mayconsist of one or more U-shaped metal layers formed atop one or moreplanar, non-U-shaped layers.

Spacers associated with the gate electrode stacks may be composed of amaterial suitable to ultimately electrically isolate, or contribute tothe isolation of, a permanent gate structure from adjacent conductivecontacts, such as self-aligned contacts. For example, in one embodiment,the spacers are composed of a dielectric material such as, but notlimited to, silicon dioxide, silicon oxy-nitride, silicon nitride, orcarbon-doped silicon nitride.

Gate contact 514 and overlying gate contact via 516 may be composed of aconductive material. In an embodiment, one or more of the contacts orvias are composed of a metal species. The metal species may be a puremetal, such as tungsten, nickel, or cobalt, or may be an alloy such as ametal-metal alloy or a metal-semiconductor alloy (e.g., such as asilicide material).

In an embodiment (although not shown), a contact pattern which isessentially perfectly aligned to an existing gate pattern 508 is formedwhile eliminating the use of a lithographic step with exceedingly tightregistration budget. In an embodiment, the contact pattern is avertically symmetric contact pattern, or an asymmetric contact patternsuch as described in association with FIG. 4J. In other embodiments, allcontacts are front-side connected and are not asymmetric. In one suchembodiment, the self-aligned approach enables the use of intrinsicallyhighly selective wet etching (e.g., versus conventionally implementeddry or plasma etching) to generate contact openings. In an embodiment, acontact pattern is formed by utilizing an existing gate pattern incombination with a contact plug lithography operation. In one suchembodiment, the approach enables elimination of the need for anotherwise critical lithography operation to generate a contact pattern,as used in conventional approaches. In an embodiment, a trench contactgrid is not separately patterned, but is rather formed between poly(gate) lines. For example, in one such embodiment, a trench contact gridis formed subsequent to gate grating patterning but prior to gategrating cuts.

In an embodiment, providing structure 500 involves fabrication of thegate stack structure 508 by a replacement gate process. In such ascheme, dummy gate material such as polysilicon or silicon nitridepillar material, may be removed and replaced with permanent gateelectrode material. In one such embodiment, a permanent gate dielectriclayer is also formed in this process, as opposed to being carriedthrough from earlier processing. In an embodiment, dummy gates areremoved by a dry etch or wet etch process. In one embodiment, dummygates are composed of polycrystalline silicon or amorphous silicon andare removed with a dry etch process including use of SF₆. In anotherembodiment, dummy gates are composed of polycrystalline silicon oramorphous silicon and are removed with a wet etch process including useof aqueous NH₄OH or tetramethylammonium hydroxide. In one embodiment,dummy gates are composed of silicon nitride and are removed with a wetetch including aqueous phosphoric acid.

Referring again to FIG. 5, the arrangement of semiconductor structure ordevice 500 places the gate contact over isolation regions. Such anarrangement may be viewed as inefficient use of layout space. In anotherembodiment, however, a semiconductor device has contact structures thatcontact portions of a gate electrode formed over an active region, e.g.,over a fin 505, and in a same layer as a trench contact via.

In an embodiment, the structure of FIG. 5 can be fabricated using aprocessing scheme involving the use of an alternate etch selectivematerial, such as described above in association with FIGS. 1A-1F and 2.In an embodiment, the alternate etch selective material includes a metaloxide selected from the group consisting of titanium oxide (TiOx),tantalum oxide (TaOx) and aluminum oxide (AlOx). In one embodiment, amixture or combination of such species can be used, such as TiAlOx.

It is to be appreciated that not all aspects of the processes describedabove need be practiced to fall within the spirit and scope ofembodiments of the present disclosure. Also, the processes describedherein may be used to fabricate one or a plurality of semiconductordevices. The semiconductor devices may be transistors or like devices.For example, in an embodiment, the semiconductor devices are ametal-oxide semiconductor (MOS) transistors for logic or memory, or arebipolar transistors. Also, in an embodiment, the semiconductor deviceshave a three-dimensional architecture, such as a tri-gate device, anindependently accessed double gate device, or a FIN-FET. One or moreembodiments may be particularly useful for fabricating semiconductordevices at a sub-10 nanometer (10 nm) technology node.

In an embodiment, as used throughout the present description, interlayerdielectric (ILD) material is composed of or includes a layer of adielectric or insulating material. Examples of suitable dielectricmaterials include, but are not limited to, oxides of silicon (e.g.,silicon dioxide (SiO₂)), doped oxides of silicon, fluorinated oxides ofsilicon, carbon doped oxides of silicon, various low-k dielectricmaterials known in the arts, and combinations thereof. The interlayerdielectric material may be formed by conventional techniques, such as,for example, chemical vapor deposition (CVD), physical vapor deposition(PVD), or by other deposition methods.

In an embodiment, as is also used throughout the present description,metal lines or interconnect line material (and via material) is composedof one or more metal or other conductive structures. A common example isthe use of copper lines and structures that may or may not includebarrier layers between the copper and surrounding ILD material. As usedherein, the term metal includes alloys, stacks, and other combinationsof multiple metals. For example, the metal interconnect lines mayinclude barrier layers (e.g., layers including one or more of Ta, TaN,Ti or TiN), stacks of different metals or alloys, etc. Thus, theinterconnect lines may be a single material layer, or may be formed fromseveral layers, including conductive liner layers and fill layers. Anysuitable deposition process, such as electroplating, chemical vapordeposition or physical vapor deposition, may be used to forminterconnect lines. In an embodiment, the interconnect lines arecomposed of a conductive material such as, but not limited to, Cu, Al,Ti, Zr, Hf, V, Ru, Co, Ni, Pd, Pt, W, Ag, Au or alloys thereof. Theinterconnect lines are also sometimes referred to in the art as traces,wires, lines, metal, or simply interconnect.

In an embodiment, as is also used throughout the present description,hardmask materials, capping layers, or plugs are composed of dielectricmaterials different from the interlayer dielectric material. In oneembodiment, different hardmask, capping or plug materials may be used indifferent regions so as to provide different growth or etch selectivityto each other and to the underlying dielectric and metal layers. In someembodiments, a hardmask layer, capping or plug layer includes a layer ofa nitride of silicon (e.g., silicon nitride) or a layer of an oxide ofsilicon, or both, or a combination thereof. Other suitable materials mayinclude carbon-based materials. Other hardmask, capping or plug layersknown in the arts may be used depending upon the particularimplementation. The hardmask, capping or plug layers maybe formed byCVD, PVD, or by other deposition methods.

In an embodiment, as is also used throughout the present description,lithographic operations are performed using 193 nm immersion lithography(i193), EUV and/or EBDW lithography, or the like. A positive tone or anegative tone resist may be used. In one embodiment, a lithographic maskis a trilayer mask composed of a topographic masking portion, ananti-reflective coating (ARC) layer, and a photoresist layer. In aparticular such embodiment, the topographic masking portion is a carbonhardmask (CHM) layer and the anti-reflective coating layer is a siliconARC layer.

In another aspect, one or more embodiments are directed to neighboringsemiconductor structures or devices separated by self-aligned gateendcap (SAGE) structures. Particular embodiments may be directed tointegration of multiple width (multi-Wsi) nanowires and nanoribbons in aSAGE architecture and separated by a SAGE wall. In an embodiment,nanowires/nanoribbons are integrated with multiple Wsi in a SAGEarchitecture portion of a front-end process flow. Such a process flowmay involve integration of nanowires and nanoribbons of different Wsi toprovide robust functionality of next generation transistors with lowpower and high performance. Associated epitaxial source or drain regionsmay be embedded (e.g., portions of nanowires removed and then source ordrain (S/D) growth is performed).

To provide further context, advantages of a self-aligned gate endcap(SAGE) architecture may include the enabling of higher layout densityand, in particular, scaling of diffusion to diffusion spacing. Toprovide illustrative comparison, FIG. 6 illustrates cross-sectionalviews taken through nanowires and fins for a non-endcap architecture(left-hand side (a)) versus a self-aligned gate endcap (SAGE)architecture (right-hand side (b)), in accordance with an embodiment ofthe present disclosure.

Referring to the left-hand side (a) of FIG. 6, an integrated circuitstructure 600 includes a substrate 602 having fins 604 protruding therefrom by an amount 606 above an isolation structure 608 laterallysurrounding lower portions of the fins 604. Upper portions of the finsmay include a relaxed buffer layer 622 and a defect modification layer620, as is depicted. Corresponding nanowires 605 are over the fins 604.A gate structure may be formed over the integrated circuit structure 600to fabricate a device. However, breaks in such a gate structure may beaccommodated for by increasing the spacing between fin 604/nanowire 605pairs.

By contrast, referring to the right-hand side (b) of FIG. 6, anintegrated circuit structure 650 includes a substrate 652 having fins654 protruding therefrom by an amount 656 above an isolation structure658 laterally surrounding lower portions of the fins 654. Upper portionsof the fins may include a relaxed buffer layer 672 and a defectmodification layer 670, as is depicted. Corresponding nanowires 655 areover the fins 654. Isolating SAGE walls 660 (which may include ahardmask thereon, as depicted) are included within the isolationstructure 652 and between adjacent fin 654/nanowire 655 pairs. Thedistance between an isolating SAGE wall 660 and a nearest fin654/nanowire 655 pair defines the gate endcap spacing 662. A gatestructure may be formed over the integrated circuit structure 600,between insolating SAGE walls to fabricate a device. Breaks in such agate structure are imposed by the isolating SAGE walls. Since theisolating SAGE walls 660 are self-aligned, restrictions fromconventional approaches can be minimized to enable more aggressivediffusion to diffusion spacing. Furthermore, since gate structuresinclude breaks at all locations, individual gate structure portions maybe layer connected by local interconnects formed over the isolating SAGEwalls 660. In an embodiment, as depicted, the SAGE walls 660 eachinclude a lower dielectric portion and a dielectric cap on the lowerdielectric portion. In accordance with an embodiment of the presentdisclosure, a fabrication process for structures associated with FIG. 6involves use of a process scheme that provides a gate-all-aroundintegrated circuit structure having epitaxial source or drainstructures.

In an embodiment, the structure of part (b) of FIG. 6 can be fabricatedusing a processing scheme involving the use of an alternate etchselective material, such as described above in association with FIGS.1A-1F and 2. In an embodiment, the alternate etch selective materialincludes a metal oxide selected from the group consisting of titaniumoxide (TiOx), tantalum oxide (TaOx) and aluminum oxide (AlOx). In oneembodiment, a mixture or combination of such species can be used, suchas TiAlOx.

A self-aligned gate endcap (SAGE) processing scheme involves theformation of gate/trench contact endcaps self-aligned to fins withoutrequiring an extra length to account for mask mis-registration. Thus,embodiments may be implemented to enable shrinking of transistor layoutarea. Embodiments described herein may involve the fabrication of gateendcap isolation structures, which may also be referred to as gatewalls, isolation gate walls or self-aligned gate endcap (SAGE) walls.

In an exemplary processing scheme for structures having SAGE wallsseparating neighboring devices, FIG. 7 illustrate cross-sectional viewsrepresenting various operations in a method of fabricating aself-aligned gate endcap (SAGE) structure with gate-all-around devices,in accordance with an embodiment of the present disclosure.

Referring to part (a) of FIG. 7, a starting structure includes ananowire patterning stack 704 above a substrate 702. A lithographicpatterning stack 706 is formed above the nanowire patterning stack 704.The nanowire patterning stack 704 includes alternating sacrificiallayers 710 and nanowire layers 712, which may be above a relaxed bufferlayer 782 and a defect modification layer 780, as is depicted. Aprotective mask 714 is between the nanowire patterning stack 704 and thelithographic patterning stack 706. In one embodiment, the lithographicpatterning stack 706 is trilayer mask composed of a topographic maskingportion 720, an anti-reflective coating (ARC) layer 722, and aphotoresist layer 724. In a particular such embodiment, the topographicmasking portion 720 is a carbon hardmask (CHM) layer and theanti-reflective coating layer 722 is a silicon ARC layer.

Referring to part (b) of FIG. 7, the stack of part (a) islithographically patterned and then etched to provide an etchedstructure including a patterned substrate 702 and trenches 730.

Referring to part (c) of FIG. 7, the structure of part (b) has anisolation layer 740 and a SAGE material 742 formed in trenches 730. Thestructure is then planarized to leave patterned topographic maskinglayer 720′ as an exposed upper layer.

Referring to part (d) of FIG. 7, the isolation layer 740 is recessedbelow an upper surface of the patterned substrate 702, e.g., to define aprotruding fin portion and to provide a trench isolation structure 741beneath SAGE walls 742.

Referring to part (e) of FIG. 7, the sacrificial layers 710 are removedat least in the channel region to release nanowires 712A and 712B.Subsequent to the formation of the structure of part (e) of FIG. 7, agate stacks may be formed around nanowires 712B or 712A, over protrudingfins of substrate 702, and between SAGE walls 742. In one embodiment,prior to formation of the gate stacks, the remaining portion ofprotective mask 714 is removed. In another embodiment, the remainingportion of protective mask 714 is retained as an insulating fin hat asan artifact of the processing scheme.

Referring again to part (e) of FIG. 7, it is to be appreciated that achannel view is depicted, with source or drain regions being locatinginto and out of the page. In an embodiment, the channel region includingnanowires 712B has a width less than the channel region includingnanowires 712A. Thus, in an embodiment, an integrated circuit structureincludes multiple width (multi-Wsi) nanowires. Although structures of712B and 712A may be differentiated as nanowires and nanoribbons,respectively, both such structures are typically referred to herein asnanowires. It is also to be appreciated that reference to or depictionof a fin/nanowire pair throughout may refer to a structure including afin and one or more overlying nanowires (e.g., two overlying nanowiresare shown in FIG. 7). In accordance with an embodiment of the presentdisclosure, a fabrication process for structures associated with FIG. 7involves use of a process scheme that provides a gate-all-aroundintegrated circuit structure having epitaxial source or drainstructures.

In an embodiment, the structure of part (e) FIG. 7 can be fabricatedusing a processing scheme involving the use of an alternate etchselective material, such as described above in association with FIGS.1A-1F and 2. In an embodiment, the alternate etch selective materialincludes a metal oxide selected from the group consisting of titaniumoxide (TiOx), tantalum oxide (TaOx) and aluminum oxide (AlOx). In oneembodiment, a mixture or combination of such species can be used, suchas TiAlOx.

In an embodiment, as described throughout, self-aligned gate endcap(SAGE) isolation structures may be composed of a material or materialssuitable to ultimately electrically isolate, or contribute to theisolation of, portions of permanent gate structures from one another.Exemplary materials or material combinations include a single materialstructure such as silicon dioxide, silicon oxy-nitride, silicon nitride,or carbon-doped silicon nitride. Other exemplary materials or materialcombinations include a multi-layer stack having lower portion silicondioxide, silicon oxy-nitride, silicon nitride, or carbon-doped siliconnitride and an upper portion higher dielectric constant material such ashafnium oxide.

To highlight an exemplary integrated circuit structure having threevertically arranged nanowires, FIG. 8A illustrates a three-dimensionalcross-sectional view of a nanowire-based integrated circuit structure,in accordance with an embodiment of the present disclosure. FIG. 8Billustrates a cross-sectional source or drain view of the nanowire-basedintegrated circuit structure of FIG. 8A, as taken along the a-a′ axis.FIG. 8C illustrates a cross-sectional channel view of the nanowire-basedintegrated circuit structure of FIG. 8A, as taken along the b-b′ axis.

Referring to FIG. 8A, an integrated circuit structure 800 includes oneor more vertically stacked nanowires (804 set) above a substrate 802. Inan embodiment, as depicted, a relaxed buffer layer 802C, a defectmodification layer 802B, and a lower substrate portion 802A are includedin substrate 802, as is depicted. An optional fin below the bottommostnanowire and formed from the substrate 802 is not depicted for the sakeof emphasizing the nanowire portion for illustrative purposes.Embodiments herein are targeted at both single wire devices and multiplewire devices. As an example, a three nanowire-based devices havingnanowires 804A, 804B and 804C is shown for illustrative purposes. Forconvenience of description, nanowire 804A is used as an example wheredescription is focused on one of the nanowires. It is to be appreciatedthat where attributes of one nanowire are described, embodiments basedon a plurality of nanowires may have the same or essentially the sameattributes for each of the nanowires.

Each of the nanowires 804 includes a channel region 806 in the nanowire.The channel region 806 has a length (L). Referring to FIG. 8C, thechannel region also has a perimeter (Pc) orthogonal to the length (L).Referring to both FIGS. 8A and 8C, a gate electrode stack 808 surroundsthe entire perimeter (Pc) of each of the channel regions 806. The gateelectrode stack 808 includes a gate electrode along with a gatedielectric layer between the channel region 806 and the gate electrode(not shown). In an embodiment, the channel region is discrete in that itis completely surrounded by the gate electrode stack 808 without anyintervening material such as underlying substrate material or overlyingchannel fabrication materials. Accordingly, in embodiments having aplurality of nanowires 804, the channel regions 806 of the nanowires arealso discrete relative to one another.

Referring to both FIGS. 8A and 8B, integrated circuit structure 800includes a pair of non-discrete source or drain regions 810/812. Thepair of non-discrete source or drain regions 810/812 is on either sideof the channel regions 806 of the plurality of vertically stackednanowires 804. Furthermore, the pair of non-discrete source or drainregions 810/812 is adjoining for the channel regions 806 of theplurality of vertically stacked nanowires 804. In one such embodiment,not depicted, the pair of non-discrete source or drain regions 810/812is directly vertically adjoining for the channel regions 806 in thatepitaxial growth is on and between nanowire portions extending beyondthe channel regions 806, where nanowire ends are shown within the sourceor drain structures. In another embodiment, as depicted in FIG. 8A, thepair of non-discrete source or drain regions 810/812 is indirectlyvertically adjoining for the channel regions 806 in that they are formedat the ends of the nanowires and not between the nanowires.

In an embodiment, as depicted, the source or drain regions 810/812 arenon-discrete in that there are not individual and discrete source ordrain regions for each channel region 806 of a nanowire 804.Accordingly, in embodiments having a plurality of nanowires 804, thesource or drain regions 810/812 of the nanowires are global or unifiedsource or drain regions as opposed to discrete for each nanowire. Thatis, the non-discrete source or drain regions 810/812 are global in thesense that a single unified feature is used as a source or drain regionfor a plurality (in this case, 3) of nanowires 804 and, moreparticularly, for more than one discrete channel region 806. In oneembodiment, from a cross-sectional perspective orthogonal to the lengthof the discrete channel regions 806, each of the pair of non-discretesource or drain regions 810/812 is approximately rectangular in shapewith a bottom tapered portion and a top vertex portion, as depicted inFIG. 8B. In other embodiments, however, the source or drain regions810/812 of the nanowires are relatively larger yet discretenon-vertically merged epitaxial structures such as nubs described inassociation with FIGS. 4A-4J.

In accordance with an embodiment of the present disclosure, and asdepicted in FIGS. 8A and 8B, integrated circuit structure 800 furtherincludes a pair of contacts 814, each contact 814 on one of the pair ofnon-discrete source or drain regions 810/812. In one such embodiment, ina vertical sense, each contact 814 completely surrounds the respectivenon-discrete source or drain region 810/812. In another aspect, theentire perimeter of the non-discrete source or drain regions 810/812 maynot be accessible for contact with contacts 814, and the contact 814thus only partially surrounds the non-discrete source or drain regions810/812, as depicted in FIG. 8B. In a contrasting embodiment, notdepicted, the entire perimeter of the non-discrete source or drainregions 810/812, as taken along the a-a′ axis, is surrounded by thecontacts 814.

Referring again to FIG. 8A, in an embodiment, integrated circuitstructure 800 further includes a pair of spacers 816. As is depicted,outer portions of the pair of spacers 816 may overlap portions of thenon-discrete source or drain regions 810/812, providing for “embedded”portions of the non-discrete source or drain regions 810/812 beneath thepair of spacers 816. As is also depicted, the embedded portions of thenon-discrete source or drain regions 810/812 may not extend beneath theentirety of the pair of spacers 816.

Substrate 802 may be composed of a material suitable for integratedcircuit structure fabrication. In one embodiment, substrate 802 includesa lower bulk substrate composed of a single crystal of a material whichmay include, but is not limited to, silicon, germanium,silicon-germanium, germanium-tin, silicon-germanium-tin, or a groupIII-V compound semiconductor material. An upper insulator layer composedof a material which may include, but is not limited to, silicon dioxide,silicon nitride or silicon oxy-nitride is on the lower bulk substrate.Thus, the structure 800 may be fabricated from a startingsemiconductor-on-insulator substrate. Alternatively, the structure 800is formed directly from a bulk substrate and local oxidation is used toform electrically insulative portions in place of the above describedupper insulator layer. In another alternative embodiment, the structure800 is formed directly from a bulk substrate and doping is used to formelectrically isolated active regions, such as nanowires, thereon. In onesuch embodiment, the first nanowire (i.e., proximate the substrate) isin the form of an omega-FET type structure.

In an embodiment, the nanowires 804 may be sized as wires or ribbons, asdescribed below, and may have squared-off or rounder corners. In anembodiment, the nanowires 804 are composed of a material such as, butnot limited to, silicon, germanium, or a combination thereof. In onesuch embodiment, the nanowires are single-crystalline. For example, fora silicon nanowire 804, a single-crystalline nanowire may be based froma (100) global orientation, e.g., with a <100> plane in the z-direction.As described below, other orientations may also be considered. In anembodiment, the dimensions of the nanowires 804, from a cross-sectionalperspective, are on the nano-scale. For example, in a specificembodiment, the smallest dimension of the nanowires 804 is less thanapproximately 20 nanometers. In an embodiment, the nanowires 804 arecomposed of a strained material, particularly in the channel regions806.

Referring to FIG. 8C, in an embodiment, each of the channel regions 806has a width (Wc) and a height (Hc), the width (Wc) approximately thesame as the height (Hc). That is, in both cases, the channel regions 806are square-like or, if corner-rounded, circle-like in cross-sectionprofile. In another aspect, the width and height of the channel regionneed not be the same, such as the case for nanoribbons as describedthroughout.

In an embodiment, the structure of FIGS. 8A-8C can be fabricated using aprocessing scheme involving the use of an alternate etch selectivematerial, such as described above in association with FIGS. 1A-1F and 2.In an embodiment, the alternate etch selective material includes a metaloxide selected from the group consisting of titanium oxide (TiOx),tantalum oxide (TaOx) and aluminum oxide (AlOx). In one embodiment, amixture or combination of such species can be used, such as TiAlOx.

In an embodiment, as described throughout, an integrated circuitstructure includes non-planar devices such as, but not limited to, afinFET or a tri-gate device with corresponding one or more overlyingnanowire structures. In such an embodiment, a correspondingsemiconducting channel region is composed of or is formed in athree-dimensional body with one or more discrete nanowire channelportions overlying the three-dimensional body. In one such embodiment,the gate structures surround at least a top surface and a pair ofsidewalls of the three-dimensional body, and further surrounds each ofthe one or more discrete nanowire channel portions.

In an embodiment, as described throughout, an underlying substrate maybe composed of a semiconductor material that can withstand amanufacturing process and in which charge can migrate. In an embodiment,the substrate is a bulk substrate composed of a crystalline silicon,silicon/germanium or germanium layer doped with a charge carrier, suchas but not limited to phosphorus, arsenic, boron, gallium or acombination thereof, to form an active region. In one embodiment, theconcentration of silicon atoms in a bulk substrate is greater than 97%.In another embodiment, a bulk substrate is composed of an epitaxiallayer grown atop a distinct crystalline substrate, e.g. a siliconepitaxial layer grown atop a boron-doped bulk silicon mono-crystallinesubstrate. A bulk substrate may alternatively be composed of a groupIII-V material. In an embodiment, a bulk substrate is composed of agroup III-V material such as, but not limited to, gallium nitride,gallium phosphide, gallium arsenide, indium phosphide, indiumantimonide, indium gallium arsenide, aluminum gallium arsenide, indiumgallium phosphide, or a combination thereof. In one embodiment, a bulksubstrate is composed of a group III-V material and the charge-carrierdopant impurity atoms are ones such as, but not limited to, carbon,silicon, germanium, oxygen, sulfur, selenium or tellurium.

Embodiments disclosed herein may be used to manufacture a wide varietyof different types of integrated circuits and/or microelectronicdevices. Examples of such integrated circuits include, but are notlimited to, processors, chipset components, graphics processors, digitalsignal processors, micro-controllers, and the like. In otherembodiments, semiconductor memory may be manufactured. Moreover, theintegrated circuits or other microelectronic devices may be used in awide variety of electronic devices known in the arts. For example, incomputer systems (e.g., desktop, laptop, server), cellular phones,personal electronics, etc. The integrated circuits may be coupled with abus and other components in the systems. For example, a processor may becoupled by one or more buses to a memory, a chipset, etc. Each of theprocessor, the memory, and the chipset, may potentially be manufacturedusing the approaches disclosed herein.

FIG. 9 illustrates a computing device 900 in accordance with oneimplementation of an embodiment of the present disclosure. The computingdevice 900 houses a board 902. The board 902 may include a number ofcomponents, including but not limited to a processor 904 and at leastone communication chip 906. The processor 904 is physically andelectrically coupled to the board 902. In some implementations the atleast one communication chip 906 is also physically and electricallycoupled to the board 902. In further implementations, the communicationchip 906 is part of the processor 904.

Depending on its applications, computing device 900 may include othercomponents that may or may not be physically and electrically coupled tothe board 902. These other components include, but are not limited to,volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flashmemory, a graphics processor, a digital signal processor, a cryptoprocessor, a chipset, an antenna, a display, a touchscreen display, atouchscreen controller, a battery, an audio codec, a video codec, apower amplifier, a global positioning system (GPS) device, a compass, anaccelerometer, a gyroscope, a speaker, a camera, and a mass storagedevice (such as hard disk drive, compact disk (CD), digital versatiledisk (DVD), and so forth).

The communication chip 906 enables wireless communications for thetransfer of data to and from the computing device 900. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 906 may implement anyof a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 900 may include a plurality ofcommunication chips 906. For instance, a first communication chip 906may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 906 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 904 of the computing device 900 includes an integratedcircuit die packaged within the processor 904. The integrated circuitdie of the processor 904 may include one or more structures, such asgate-all-around integrated circuit structures fabricated using alternateetch selective material, built in accordance with implementations ofembodiments of the present disclosure. The term “processor” may refer toany device or portion of a device that processes electronic data fromregisters and/or memory to transform that electronic data into otherelectronic data that may be stored in registers and/or memory.

The communication chip 906 also includes an integrated circuit diepackaged within the communication chip 906. The integrated circuit dieof the communication chip 906 may include one or more structures, suchas gate-all-around integrated circuit structures fabricated usingalternate etch selective material, built in accordance withimplementations of embodiments of the present disclosure.

In further implementations, another component housed within thecomputing device 900 may contain an integrated circuit die that includesone or structures, such as gate-all-around integrated circuit structuresfabricated using alternate etch selective material, built in accordancewith implementations of embodiments of the present disclosure.

In various implementations, the computing device 900 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 900 may be any other electronic device that processes data.

FIG. 10 illustrates an interposer 1000 that includes one or moreembodiments of the present disclosure. The interposer 1000 is anintervening substrate used to bridge a first substrate 1002 to a secondsubstrate 1004. The first substrate 1002 may be, for instance, anintegrated circuit die. The second substrate 1004 may be, for instance,a memory module, a computer motherboard, or another integrated circuitdie. Generally, the purpose of an interposer 1000 is to spread aconnection to a wider pitch or to reroute a connection to a differentconnection. For example, an interposer 1000 may couple an integratedcircuit die to a ball grid array (BGA) 1006 that can subsequently becoupled to the second substrate 1004. In some embodiments, the first andsecond substrates 1002/1004 are attached to opposing sides of theinterposer 1000. In other embodiments, the first and second substrates1002/1004 are attached to the same side of the interposer 1000. And infurther embodiments, three or more substrates are interconnected by wayof the interposer 1000.

The interposer 1000 may be formed of an epoxy resin, afiberglass-reinforced epoxy resin, a ceramic material, or a polymermaterial such as polyimide. In further implementations, the interposer1000 may be formed of alternate rigid or flexible materials that mayinclude the same materials described above for use in a semiconductorsubstrate, such as silicon, germanium, and other group III-V and groupIV materials.

The interposer 1000 may include metal interconnects 1008 and vias 1010,including but not limited to through-silicon vias (TSVs) 1012. Theinterposer 1000 may further include embedded devices 1014, includingboth passive and active devices. Such devices include, but are notlimited to, capacitors, decoupling capacitors, resistors, inductors,fuses, diodes, transformers, sensors, and electrostatic discharge (ESD)devices. More complex devices such as radio-frequency (RF) devices,power amplifiers, power management devices, antennas, arrays, sensors,and MEMS devices may also be formed on the interposer 1000. Inaccordance with embodiments of the disclosure, apparatuses or processesdisclosed herein may be used in the fabrication of interposer 1000 or inthe fabrication of components included in the interposer 1000.

Thus, embodiments of the present disclosure include gate-all-aroundintegrated circuit structures fabricated using alternate etch selectivematerial, and the resulting structures.

The above description of illustrated implementations of embodiments ofthe disclosure, including what is described in the Abstract, is notintended to be exhaustive or to limit the disclosure to the preciseforms disclosed. While specific implementations of, and examples for,the disclosure are described herein for illustrative purposes, variousequivalent modifications are possible within the scope of thedisclosure, as those skilled in the relevant art will recognize.

These modifications may be made to the disclosure in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the disclosure to the specific implementationsdisclosed in the specification and the claims. Rather, the scope of thedisclosure is to be determined entirely by the following claims, whichare to be construed in accordance with established doctrines of claiminterpretation.

Example embodiment 1: An integrated circuit structure includes avertical arrangement of horizontal nanowires. A gate stack is over thevertical arrangement of horizontal nanowires. A pair of dielectricspacers is along sides of the gate stack and over the verticalarrangement of horizontal nanowires. A metal oxide material is betweenadjacent ones of the vertical arrangement of horizontal nanowires at alocation between the pair of dielectric spacers and the sides of thegate stack.

Example embodiment 2, the integrated circuit structure of exampleembodiment 1, wherein the metal oxide material is a metal oxide selectedfrom the group consisting of titanium oxide (TiOx), tantalum oxide(TaOx) and aluminum oxide (AlOx).

Example embodiment 3, the integrated circuit structure of exampleembodiment 1 or 2, wherein the pair of dielectric spacers includes adielectric material selected from the group consisting of siliconnitride, silicon oxynitride, silicon oxide, and carbon-doped siliconnitride.

Example embodiment 4, the integrated circuit structure of exampleembodiment 1, 2 or 3, wherein the gate stack includes a high-k gatedielectric layer and a metal gate electrode.

Example embodiment 5, the integrated circuit structure of exampleembodiment 4, wherein the high-k gate dielectric layer includes a metaloxide gate dielectric material different than the metal oxide material.

Example embodiment 6, the integrated circuit structure of exampleembodiment 1, 2, 3, 4 or 5, further including a pair of epitaxial sourceor drain structures at first and second ends of the vertical arrangementof horizontal nanowires.

Example embodiment 7, the integrated circuit structure of exampleembodiment 6, wherein the pair of epitaxial source or drain structuresis a pair of discrete epitaxial source or drain structures.

Example embodiment 8, the integrated circuit structure of exampleembodiment 6, wherein the pair of epitaxial source or drain structuresis a pair of non-discrete epitaxial source or drain structures.

Example embodiment 9, the integrated circuit structure of exampleembodiment 1, 2, 3, 4, 5, 6, 7 or 8, wherein the vertical arrangement ofhorizontal nanowires is over a subfin, and the metal oxide material isfurther between the subfin and a bottommost nanowire of the verticalarrangement of horizontal nanowires at a location between the pair ofdielectric spacers and the sides of the gate stack.

Example embodiment 10, the integrated circuit structure of exampleembodiment 9, wherein the subfin includes a portion of a bulk siliconsubstrate.

Example embodiment 11, the integrated circuit structure of exampleembodiment 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the nanowires of thevertical arrangement of horizontal nanowires include silicon.

Example embodiment 12: A method of fabricating an integrated circuitstructure includes forming a plurality of alternating active layers andfirst sacrificial layers above a substrate. The plurality of alternatingactive layers and first sacrificial layers is patterned to form a fin.One or more sacrificial clamping pillars are formed over the fin. Thefirst sacrificial layers are removed from the fin. Second sacrificiallayers are formed in place of the first sacrificial layers in the fin.The one or more sacrificial clamping pillars are removed.

Example embodiment 13, the method of example embodiment 12, furtherincluding forming a dummy gate structure over the fin. Sidewall spacersare formed along sides of the dummy gate structure. The dummy gatestructure is removed. The second sacrificial layers are removed inlocations of the removed gate structure to release nanowire portions ofthe alternating active layers. A permanent gate structure is formed overthe nanowire portions of the alternating active layers and between thesidewall spacers.

Example embodiment 14, the method of example embodiment 12 or 13,wherein the active layers include silicon, the first sacrificial layersinclude silicon germanium, and the second sacrificial layers include ametal oxide selected from the group consisting of titanium oxide (TiOx),tantalum oxide (TaOx) and aluminum oxide (AlOx).

Example embodiment 15: A computing device includes a board, and acomponent coupled to the board. The component includes an integratedcircuit structure including a vertical arrangement of horizontalnanowires. A gate stack is over the vertical arrangement of horizontalnanowires. A pair of dielectric spacers is along sides of the gate stackand over the vertical arrangement of horizontal nanowires. A metal oxidematerial is between adjacent ones of the vertical arrangement ofhorizontal nanowires at a location between the pair of dielectricspacers and the sides of the gate stack.

Example embodiment 16: The computing device of example embodiment 15,further including a memory coupled to the board.

Example embodiment 17: The computing device of example embodiment 15 or16, further including a communication chip coupled to the board.

Example embodiment 18: The computing device of example embodiment 15, 16or 17, wherein the component is a packaged integrated circuit die.

Example embodiment 19: The computing device of example embodiment 15,16, 17 or 18, wherein the component is selected from the groupconsisting of a processor, a communications chip, and a digital signalprocessor.

Example embodiment 20: The computing device of example embodiment 15,16, 17, 18 or 19, wherein the computing device is selected from thegroup consisting of a mobile phone, a laptop, a desk top computer, aserver, and a set-top box.

What is claimed is:
 1. An integrated circuit structure, comprising: avertical arrangement of horizontal nanowires; a gate stack over thevertical arrangement of horizontal nanowires; a pair of dielectricspacers along sides of the gate stack and over the vertical arrangementof horizontal nanowires; and a metal oxide material between adjacentones of the vertical arrangement of horizontal nanowires at a locationbetween the pair of dielectric spacers and the sides of the gate stack.2. The integrated circuit structure of claim 1, wherein the metal oxidematerial is a metal oxide selected from the group consisting of titaniumoxide (TiOx), tantalum oxide (TaOx) and aluminum oxide (AlOx).
 3. Theintegrated circuit structure of claim 1, wherein the pair of dielectricspacers comprises a dielectric material selected from the groupconsisting of silicon nitride, silicon oxynitride, silicon oxide, andcarbon-doped silicon nitride.
 4. The integrated circuit structure ofclaim 1, wherein the gate stack comprises a high-k gate dielectric layerand a metal gate electrode.
 5. The integrated circuit structure of claim4, wherein the high-k gate dielectric layer comprises a metal oxide gatedielectric material different than the metal oxide material.
 6. Theintegrated circuit structure of claim 1, further comprising: a pair ofepitaxial source or drain structures at first and second ends of thevertical arrangement of horizontal nanowires.
 7. The integrated circuitstructure of claim 6, wherein the pair of epitaxial source or drainstructures is a pair of discrete epitaxial source or drain structures.8. The integrated circuit structure of claim 6, wherein the pair ofepitaxial source or drain structures is a pair of non-discrete epitaxialsource or drain structures.
 9. The integrated circuit structure of claim1, wherein the vertical arrangement of horizontal nanowires is over asubfin, and the metal oxide material is further between the subfin and abottommost nanowire of the vertical arrangement of horizontal nanowiresat a location between the pair of dielectric spacers and the sides ofthe gate stack.
 10. The integrated circuit structure of claim 9, whereinthe subfin comprises a portion of a bulk silicon substrate.
 11. Theintegrated circuit structure of claim 1, wherein the nanowires of thevertical arrangement of horizontal nanowires comprise silicon.
 12. Amethod of fabricating an integrated circuit structure, the methodcomprising: forming a plurality of alternating active layers and firstsacrificial layers above a substrate; patterning the plurality ofalternating active layers and first sacrificial layers to form a fin;forming one or more sacrificial clamping pillars over the fin; removingthe first sacrificial layers from the fin; forming second sacrificiallayers in place of the first sacrificial layers in the fin; and removingthe one or more sacrificial clamping pillars.
 13. The method of claim12, further comprising: forming a dummy gate structure over the fin;forming sidewall spacers along sides of the dummy gate structure;removing the dummy gate structure; removing the second sacrificiallayers in locations of the removed gate structure to release nanowireportions of the alternating active layers; and forming a permanent gatestructure over the nanowire portions of the alternating active layersand between the sidewall spacers.
 14. The method of claim 12, whereinthe active layers comprise silicon, the first sacrificial layerscomprise silicon germanium, and the second sacrificial layers comprise ametal oxide selected from the group consisting of titanium oxide (TiOx),tantalum oxide (TaOx) and aluminum oxide (AlOx).
 15. A computing device,comprising: a board; and a component coupled to the board, the componentincluding an integrated circuit structure, comprising: a verticalarrangement of horizontal nanowires; a gate stack over the verticalarrangement of horizontal nanowires; a pair of dielectric spacers alongsides of the gate stack and over the vertical arrangement of horizontalnanowires; and a metal oxide material between adjacent ones of thevertical arrangement of horizontal nanowires at a location between thepair of dielectric spacers and the sides of the gate stack.
 16. Thecomputing device of claim 15, further comprising: a memory coupled tothe board.
 17. The computing device of claim 15, further comprising: acommunication chip coupled to the board.
 18. The computing device ofclaim 15, wherein the component is a packaged integrated circuit die.19. The computing device of claim 15, wherein the component is selectedfrom the group consisting of a processor, a communications chip, and adigital signal processor.
 20. The computing device of claim 15, whereinthe computing device is selected from the group consisting of a mobilephone, a laptop, a desk top computer, a server, and a set-top box.